Turbodrill thrust balancing apparatus



April 8, 1952 W- R, POSTLEWAITE 2,592,519

TURBODRILL THRUST BALANCING APPARATUS Filed Nov. 8. 1948 INVENTOR Wi IIiam R. Posrlewaife ATTORNEYS Patented Apr. 8, 1952 UNITED STATES PATENTOFFICE TURBODRILL THRUST BALANCING APPARATUS corporation of DelawareAppiicationNox/'ember 8, 1948, Serial No. 58,971

1 Claim. 1

The present invention relates towell drilling units of the fluid driventurbine type and more particularly to axial thrust balancingv means forsuch turbines.

In the drilling of oil wells by means of iiuid driven turbines locatedadjacent the drilling bit in the bore hole, the chief factor limitingthe successful operation of the turbine over an eX- tended period oftime has been the thrust bearings provided for such turbines. The reasonfor this diiiiculty has been that in using drilling fluid for drivingthe turbine, it is customary for the drilling fluid to act as aconveying medium for carrying the cuttings from the drill bit tothesurfacev and then recirculating the return fluid. In this process thedrilling fluid very soon becomes contaminated with sand or otherabrasive material in the cuttings, and even with elaborate means forcleaning the drilling fluid a great deal of this material isrecirculated with the drilling uid. ln passing through the turbine thismaterial acts as an. abrading substance on the elements of the turbine.This abrading action is especially severe upon the bearings of theturbine which are usually lubricated by the drilling uid. In order tocompensate for the abrading action of the drilling fluid, it hasheretofore been proposed to use extremely hard ball bearings to absorbthe normal thrust produced on the turbine shaft by the reaction of thedrilling iiuid pressure on the vanes or buckets mounted on the turbineshaft. While it has been proposed to isolate the4 bearings of theturbine as in regular turbines, well drilling turbines are subject tospace limitations not encountered inV any other type` of turbine and dueto the inaccessibility of the unit during operation, the turbine mustbemaintained as simple'in construction as possible.

It is an object of the present invention to provide thrust balancingmeans which will adequately balance the axial thrust on the turbineshaft produced by the drilling uid pressure acting against the rotataryvanes of the turbine shaft.

It is a further object of this invention to provide a longer wearingaxial thrust balancing means for a turbodrill unit.

A still further object of this invention is to provide a turbodrillthrust balancing means of simple and rugged construction and inexpensivein both initial outlay and upkeep cost during the life of the turbineunit.

Further objects and advantages of the present invention will becomeapparent from the following description taken in conjunction with theaccompanying drawing.

In the drawing:

Fig. 1 is a cross-sectional view of a turbodrill unit connected to adrill casing havingaxial thrust balancing means according to the presentinvention.

Fig. 2 is a cross-sectional View in the direction of arrows- 2-2 in Fig.l.

Fig. 3 isa cross-sectional view in the direction of arrows. 3"-3 in.Fig. l.

Fig. 4 is a cross-sectional view taken in the direction of arrows 4:-4in Fig. 1, showing theV turbine buckets or vanes of the turbine rotor.

As shownV in. the drawing a drill. casi-ng I is connected to a turbinehousing 2 by means of a coupling 3. which is. Welded to the turbinehousing E by means of a weld 4. Coupling 3 is connected to casing I bymeans of a threaded section 5 so that the turbine housing 2 may beeasily disconnected from drill casing I, but rigidly connected' duringthe operation of the turbine in the well'. In order to control thespacing of the stationary vanes 6 in the turbine, vanes 6' are mountedupon sleeve members I which have an outside` diameter adapted to closelyengage the inside diameter of the turbine housing 2, and as shown, anynumber of turbine stages may be provided by merely assembling aplurality of sleeves'I which carry the vanes 6 within housing 2. Thevanes inv turn provide Support for radial bearingsof the turbine shaft 8by an annular ring S; which supports a rubber sleeve IB. Turbine shaft8, is` provided with a plurality of rotating vanes,4 or buckets, I I,which are rotatably mounted on. shaft 8 by means of a hub section lf2which has a conically tapered section I3 adapted to mate with a conicalbore i5 in hub I4 of the vanes II. Hub I4 is provided with an annulargroove I6 adjacent the upper end of the vanes I I which is adapted toreceive a retaining ring I'I. Ring I'I has a threaded section adapted toengage a corresponding threaded section on the upper end of hub I2. InorderV to protect the shaft 8 from undue wear, hub I2A is provided withan axially extending section I8 adapted to provide the journal surfacewith rubber sleeve Ill. Y

It will be understood by those skilled in the art that in the operationof a turbodrill unit, drilling; fluid is introduced to the turbinethrough casing I and then passes through the turbine housing 2Y to therst. stage of the stationaryY vanes 6. Vanes 6 direct the iiow of fluidto the vanes or buckets II which are rigidly mountedv for rotation uponthey turbine shaft 8. After fluid passes vanes II, wherein a portion ofthe iiuid pressure on the fluid is converted to rotational energy, thefiuid passes to succeeding stages of stationary vanes 6 and rotatingvanes II. The number of succeeding stages is entirely dependent upon thedesigned power rating of the turbine unit and does not form any part ofthe present invention. It will be appreciated that the action of thefluid pressure upon vanes II will tend to exert a downward axial thrustupon shaft 8 so that the shaftV is unbalanced in a downward direction.In the usual arrangement a thrust bearing lis provided between shaft 8`and hous-` ing 2 to counterbalance this axial thrust. However, by thepresent invention means are provided for counterbalancing the axialthrust Without the inherent limitations presented by the usual ballthrust bearings when the drilling fluid contains abrasive material. Toprovide the desired counterbalancing axial thrust upon the shaft 8 athreaded section I9 is provided on the end of shaft 8 which is adaptedto engage a threaded bore 20 in a piston means 2|. When piston means 2|is thus assembled, it is adapted to rotate with shaft 8. Piston 2| inturn is adapted to engage a cylinder means 22 which extends axiallyabove the first stage of the turbine. Cylinder means 22 is provided witha bore 23 concentric with casing 2, and preferably, but not necessarily,a cylinder lining member 24 of a wear-resisting material may be insertedin the bore 23. Piston means 2| may be provided with a rubber sleeve 25so that the wear between the cylinder and piston will be between rubbersleeve 25 and the cylinder lining 24. In order to lubricate sleeve 25and lining 24, rubber sleeve 25 may be provided with either a single ordouble helical groove 28 cut in the surface thereof and extending alongthe length of sleeve 25.

In order to maintain substantially the same pressure differential acrosspiston 2| as the pressure differential across the turbine, the top ofbore 23 is provided with vent conduit means to the outside of theturbine housing by four bore holes 21 which communicate with an annularring 28 cut in the external diameter of cylinder means 22 which in turncommunicates with four holes 29 in the turbine housing 2. In order toseal the vent conduit means from the high pressure fluid a pair ofannular seals 30, which may be O-rings, are provided in grooves 3| cuton either side of the annular groove 28. Conduiting of the high pressurefluidI from casing to the turbine vanes is provided by passages 32 incylinder means 22, as shown in Fig. 2, which in turn communicate throughpassageways 33 to the annular space 34 between casing 2 and cylindermeans 22. Flow of fluid is axial along the length of the piston andcylinder in annular space 34 and then is admitted to the turbine vanesthrough six openings 35 above ring 36 which serves as the lower supportof the cylinder means 22. Ring 38 engages the inner diameter of theturbine housing 2 so that cylinder means 22 is concentrically locatedwithin housing 2. A ring member 31 having a thereaded portion 38 adaptedto engage a threaded portion of coupling 3 and supporting ring 1 on therst stationary varies serve to 1ocate cylinder means 22 axially. It willbe understood that suitable means will be provided at the lower end ofthe turbine housing to hold the successive rings 1 and cylinder means 22in abutting relationship. It will also be understood that a thrustbearing will be provided at the lower end of the turbine between shaft 8and housing 2.

In operation the drilling fluid is introduced through casing 2 to fluidpassages 32 in the cylinder means, and then through openings 33 to theannular space 34 dened by casing 2 and cylinder means 22 and through theopenings 35 in supporting ring 36 to the rst stage of the turbine.However, since the lower end of piston means 2| is likewise open to thehigh pressure fluid, the fluid pressure will not only act downward uponthe rotating vanes but will also exert an upward axial thrust upon theface of piston means 2|.- As mentioned hereinbefore, the

cylinder head pressure is maintained at substantially the pressure atthe lower end of the turbine by means of vent holes 21 and the annularpassage 28 which is in communication with holes 29 through the turbinehousing 2.

While the present invention does not necessarily eliminate the thrustbearing in this type of turbine unit, it will be apparent that since themajor thrust upon the shaft is balanced by the rotating piston means,the thrust bearing may be constructed of cheaper materials and greatermanufacturing and operating tolerances are permissible in the turbine.Accordingly, substantial savings may be effected in the initial cost anddue to the greater durability of the thrust bearing under reducedloading the maintenance cost of the turbine is greatly reduced.

It will be apparent to those skilled in the art that various changes andmodifications may be made for conduiting the operating fiuid from abovethe cylinder means to the first stage of the turbine. In particular itwould be possible to introduce the fiuid through the shaft of theturbine and locate the cylinder and piston adjacent the periphery of theturbine housing. In this arrangement it would be possible to obtain agreater surface for the fluid to act against since the effective area ofthe piston face could be increased due to the greater diameter of thepiston that could be acted upon. However, this is entirely a matter ofchoice and will be determined by the number of stages through which thefluid must pass in the turbine and the total pressure differentialacross the turbine to be balanced by the piston.

Further changes and modification in the present invention may be madewithout departing from the spirit thereof, and I therefore intend tolimit the invention only within the scope of the appended claim.

I claim:

A thrust balancing cylinder for an axial flow drilling mud fluid driventurbine with a vaned shaft mounted in a ported tubular housing andhaving a piston secured to the top of said turbine shaft, comprising acylindrical member secured in the drilling fluid inlet of said tubularhousing, a bore in said member closed at one end and open at theopposite end to receive said piston, centering means at each end of saidcylinder to align it in said housing, means on said cylinder cooperatingwith said housing to form a drilling fluid bypass from the upper end ofsaid cylinder to the lower end thereof independently of said bore, meansforming a passage from the closed end of said bore to a port of saidhousing, and sealing means for said last-named passage-forming means.

WILLIAM R. POSTLEWAITE.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 833,990 Webster Oct. 23, 1906887,595 Darlington May l2, 1908 899,559 Pfau Sept. 29, 1908 961,087Patitz June 7, 1910 1,071,420 Hodgkinson Aug. 26, 1913 1,344,193 WilsonJune 22, 1920 1,476,747 Wolever Dec. 11, 1923 2,348,047 Yost May 2, 1944

